1. Field of the Invention
The present invention relates to, for example, a label usable for an anti-counterfeit purpose, and an adhesive label and a printed product including the same.
2. Description of the Related Art
In recent years, counterfeit articles circulating on the market have developed into a serious social issue. As a countermeasure, for example, a label that enables authenticity confirmation is put on an article. Examples of such labels or so-called anti-counterfeit labels are a label including a printed layer formed by a functional ink such as fluorescent ink or OVI (Optically Variable Ink), a label including a printed layer formed by special printing such as microprinting or intaglio printing, a label including a hologram or a diffraction grating, a label in which information is written by magnetic recording, and a label including an IC (Integrated Circuit) tag.
Many anti-counterfeit labels are themselves difficult to counterfeit. However, some anti-counterfeit labels can relatively easily be peeled off articles on which they are put. Such labels may be used dishonestly by peeling such labels off used articles and putting them on counterfeit articles.
Some anti-counterfeit labels employ measures to make such reuse impossible.
For example, an anti-counterfeit label has a notch. Such an anti-counterfeit label is designed to tear from the notch position when ripped off an article on which it is put.
Another anti-counterfeit label uses a base that causes brittle fracture by a relatively small force. Such a label is also designed to break when ripped off an article on which it is put.
Still another anti-counterfeit label includes a brittle layer that causes brittle fracture by a relatively small force. The adhesive strength between the brittle layer and a layer adjacent on the observer side changes depending on the position. When this label is ripped off an article on which it is put, the brittle layer breaks in a pattern corresponding to the adhesive strength distribution. As a result, for example, the brittle layer and the like partially remain on the article with a pattern corresponding to a character string “VOID”. A missing portion having a pattern corresponding to the character string “VOID” is formed in the brittle layer and the like of the anti-counterfeit label.
It is impossible or difficult to reuse such an anti-counterfeit label ripped off and released from an article. However, an organic solvent soaking into the adhesive layer or bonding layer may make it possible to release the anti-counterfeit label without damaging the label main body.
Some anti-counterfeit labels employ a technique of making this impossible or difficult.
For example, an anti-counterfeit label uses, as the material of an adhesive layer, a mixture of an adhesive and an additive insoluble in it (for example, see patent literature 1). When this anti-counterfeit label is released using an organic solvent, the surface of the adhesive layer becomes uneven due to the difference in solubility to the organic solvent between the adhesive and the additive.
Another anti-counterfeit label uses a printed layer containing a dye soluble in an organic solvent (for example, see patent literature 2). When this anti-counterfeit label is released using an organic solvent, the dye seeps from the printed layer.
Note that this label can be released without damage to the label main body or seepage of the dye when the surface is heated using a drier or the like. As an anti-counterfeit label taking a measure against the release by heating, there is, for example, an anti-counterfeit label using an adhesive layer containing foaming particles that foams when heated (for example, see patent literature 3).
It is impossible or difficult to reuse these anti-counterfeit labels released using an organic solvent or heat. However, after the expiration date of an article, the possibility that the anti-counterfeit label is removed together with the surface of the article on which it is put needs to be taken into consideration. The above-described measures cannot prevent reuse of an anti-counterfeit label removed in this way.